Nortel Networks Corporation

Northern Telecom Limited

Apple Inc.

Research in Motion Corporation

John Edward Hudson

Christopher John Reed

Simon John Gale

David Damian Nicholas Bevan

Francis Giles Overbury

David G Steer

Martin Stevens Smith

Keith Russell Edwards

Koon Hoo Teo

Bassam M Hashem

Robin Paul Rickard

Andrew William Jeffries

Julius Robson

Keith S Wilson

Daniel Boudreau

Christopher Robert Ward

John Thompson

Paul Barton

A communications system comprising a base station, and a plurality of terminals served by that base station which may include an ad-hoc network of terminals. Information from the base station or transmitting terminal is transported to the receiving terminals in the form of symbols in an orthogonal frequency division multiplexed format. Each terminal has means for measuring a channel dispersion and rate of phase variation corresponding to multipath signal reception for that terminal and for reporting that dispersion and variation measure to the transmitting station. In response to the channel dispersion and phase change measurements, the base station or transmitting terminal is arranged to provide, for groups of terminals having a similar channel dispersion, respective symbol and prefix lengths on the basis of the dispersion measurement of that group of terminals.

OFDM communications system

A scheme is provided for allocating spectral resource made up of a plurality of resource units in a multiple access wireless link linking a partition of a base station and at least one child user equipment of the partition in a wireless communications network. According to the scheme the same fixed allocation of resource units is made to each user equipment of the network. According to one embodiment a measure of a maximum likely number of child user equipments per partition of the network is determined. Then a fixed allocation of resource units based on the ratio of the number of resource units per unit time to the measure is calculated. Then the same fixed allocation of resource units is allocated to each child user equipment across the network. In one embodiment resource units which are not allocated in the fixed allocation remain unallocated to user equipments. In another embodiment the remaining resource units are allocated among the child user equipments by prioritizing user equipments having a high gain link. Also provided is a communications network and a resource allocation controller for a communications network which use the above scheme.

Method of resource allocation in a multiple access wireless communications network

Space division multiple access scheduling for a transmitter having an antenna array with multiple beams includes determining, and storing at the transmitter, angles of arrival of signals and identifiers from user equipments, such as cellular telephones. The user equipment identifiers are sorted at the transmitter in order of angle of arrival to form an ordered list. The ordered list is subdivided into ordered sub-lists of user equipment identifiers in order of angle of arrival. The transmitter sequentially transmits simultaneously to a group of each respective ordinal member of each sub-list of user equipments, which are well-spaced.

Space division multiple access scheduling

Capacity of radio links in an in-building cellular communication system is currently limited by bandwidth available for a communications link between a terminal and a single base station. The present invention mitigates this limitation by permitting the terminal to establish a number of communications links with a number of base stations. Content data is distributed in parallel over the number of communications links.

Wireless communications method, system and terminal therefor utilising a plurality of simultaneous, data bearing, communications links for conveying data between a plurality of base stations and a terminal

Equalisation of a communication channel is achieved through use of a Wiener filter frequency response mechanism that operates to transform at least a portion of a data stream generated from a plurality of space time coded (STC) symbol streams received from a plurality of transmit antenna elements into a packet spectrum. A training sequence for a channel through which the symbol streams have been sent is also transformed to a channel impulse response spectrum in order to assess the channel impulse response for the channel. The packet spectrum is equalised with the channel impulse response spectrum to produce an equalised packet spectrum in the transform domain. This is then converted into a time domain equalised data stream for recovery of originally transmitted information.

Equaliser for digital communications systems and method of equalisation

It is becoming increasingly important to improve data throughput in wireless networks. By transmitting data simultaneously at different modulation amplitudes and/or using different code strengths, terminals having different carrier to noise ratios are able to decode the different amplitude levels with varying degrees of success. This allows distant terminals to receive low data rate transmissions at high modulation levels or code rates while nearer terminals can use additional capacity in the transmission by receiving lower level modulation signals or code rates. In this way, distant terminals do not degrade overall network performance. By arranging for terminals to acknowledge receipt of data, retransmission at different modulation levels or code rates may be carried out by the base station in order to improve performance in the presence of noise without a priori knowledge of the carrier to noise ratio for a particular terminal.

Methods and apparatus for transmitting and receiving data over a communications network in the presence of interference

Multiple Steiner codes are transmitted as bursts from multiple base stations () having one or more transmit elements (), with successive bursts providing an extended training sequence for use in channel estimation at an addressed unit (), such as a mobile handset. Accurate channel estimation is possible through the use of Wiener frequency domain MMSE deconvolution () combined with frequency domain spatial decoupling matrices, with quasi-orthogonal pseudo-noise sequences () allocated to base stations and their antenna elements. The use of Steiner codes to supplement Wiener frequency domain MMSE deconvolution and frequency domain spatial decoupling results in the possibility of allocating only a single training sequence to each base station provided that the training sequence is of sufficient length to encompass all multiple time-translated channel impulse responses (H). Estimates may be refined iteratively by minimising the MS error of demodulated pilot symbols. Estimates may also be refined by removing taps from the impulse response which are insignificant based on a relatively long-term power-delay profile for the channel.

Communication system and methods of estimating channel impulse responses therein

The use of cyclic prefixes with OFDM transmissions is known. Typically the prefix length is chosen to be at least as long as the duration of significant multipath in the transmission channel. However, OFDM has disadvantages in terms of DSP load and transmitter power amplifier specifications. The use of a cyclic prefix with periodic CDMA codes has been found to yield equivalent performance in terms of orthogonality in a dispersive channel and yet overcomes the disadvantages of cyclicly prefixed OFDM transmissions. Examples are given of Walsh Hadamard binary periodic codes.

Methods and apparatus for transmitting data over a CDMA network

In a cellular mobile telecommunications system the position of a mobile station can be estimated in terms of its bearing and range from a cell site. A multi-element direction finding antenna at the cell site receives signals from the mobile station and a receiver circuit estimates the bearing using the relative phase of signals received at different antenna elements and estimates the range by measuring round trip delay of signals to and from the mobile station. Motion of the mobile station can introduce errors into the bearing estimate due to frequency offset and frequency spread when element sampling is non-simultaneous. Compensation for these errors is introduced by using signal samples successively received at the same antenna element to estimate Doppler frequency offset and spread. It is necessary to ensure accurate calibration of the direction finding antenna and the receiver circuit. This is done by injecting calibration signals into the circuit near the antenna or into the antenna itself from a near field probe. Other aspects of calibration, such as antenna position, are calibrated using a remote beacon. A beacon emulating a mobile station but at a fixed, known location, or a beacon at an adjacent cell site may be used.

Position location method and apparatus for a mobile telecommunications system

The disclosure relates to wireless communications such as cdma systems where variable orthogonal spreading factors are employed. Code words are selected from a representation known as the orthogonal variable spreading factor (OVSF) tree, which allows code words of different length to be mixed yet remain orthogonal. The present invention provides a system whereby a subset of codes are employed whereby the bit rate can be reduced. This is of particular advantage under poor propagation conditions. Mutual interference between users is reduced.

Spreading code selection process for equalization in CDMA communications systems

The present invention provides a method whereby an adaptive equaliser is applied to the terminal (mobile) receivers in a cellular radio CDMA system whose purpose is to minimise the mutual interference between users sharing the same radio channel. The application relevant to third generation cellular systems which consist of UTRA (or WBCDMA) in Europe and CDMA2000 in the USA (or future merged standards variants of these systems), and has a special application to the time domain duplex (TDD) mode of these systems. An algorithm is provided whereby the equaliser is adapted to conform to some recognised optimality criterion which is known to lead to a minimum mutual interference situation. One method is the constrained minimum output finite impulse response (FIR) digital filter power condition, but the technique is not limited to this criterion. The method reduces the computation load of a digital filter by selecting a sparse subset of delay line taps which are actively weighted and used as a filter. The rest of the delay line taps are ignored. The active subsets are optimized.

Channel equalisers

The invention relates to sub macro cellular layers of a wireless communications system. An object of wireless communications system design is to reduce the number of base station sites required by increasing their range and or capacity. The term, &ldquo;capacity&rdquo; is used herein to refer to any suitable measure which provides an indication of how many conventional mobile terminals or other terminals are able to communicate effectively with a given antenna arrangement. Macro base station sites for cellular systems are particularly expensive, both in terms of the equipment required and the need for a geographical site for each cell site where, inter alia, large structures are frequently employed where planning permission is required. The present invention seeks to provide a system and method for reducing the effects of adjacent channel interference, especially in 3G CDMA base stations.

Sub-macro cellular base station

The present invention relates to radio communication antennas and in particular relates to multi-user detection for CDMA antenna array receivers. Here is provided a method of operating a FDD radio communications system wherein a base station has a constrained beamformer comprising at least two antennas with L channel taps and is operable to maximize diversity gain at the mobile. The total SNR of all the multipath components received at the mobile will be less than for the maximum SNR algorithm, but the diversity gain should outweigh this loss for (nearly) orthogonal channel taps. The performance of an uplink fixed weight beamformer is determined from the correlation matrix of the fadings of the uplink sampled impulse response. Computation techniques are simplified and processing time can be considerably reduced.

Growing community of inventors

Stansted, United Kingdom

John Edward Hudson